The invention relates to containers for use with a method of preparing concrete in which the quantities of cement and aggregate are measured and stored separately in one or more containers at a central supply station where the solid raw materials are present, said containers are then brought to the site, where the whole contents of the container or containers and the quantity of water required for the specific quantities of solids are deposited in a concrete mixer, the solids and the water are mixed to the required degree in the mixer, and the ready-mixed concrete is used immediately on the site. This enables freshly mixed concrete to be used at any time, such concrete being mixed according to requirements. Deliveries of the appropriate measured quantities of solids in containers are not restricted to the same timetable as the use of concrete on the building site. The containers may be delivered at any suitable time during the working day. The raw materials can always be kept ready, so that there is never any need to wait. Simple containers and standard trucks to transport these containers can be used. Conventional concrete mixers can be used to mix the concrete. The space required on the site for the purposes of supplying the raw materials and preparing the concrete can be very limited. Another important advantage is that the process of measuring out the quantities of cement and aggregate into the containers at the supply station is independent of requirements at any given time at each of the building sites supplied from this supply station.
The quantities of cement, aggregate and water can be so determined that the concrete has a specific quality. Consequently, it is possible to satisfy the highest standards as regards concrete quality at the site. An advantage is that the quantities of cement can be kept lower than otherwise required to achieve a given quality because only freshly prepared concrete is used.
The measured quantities of cement and aggregate can be placed in the natural state in separate compartments of a container. The advantage of this is that with a specific container the required quantities of cement and aggregate are immediately available so that the use of a specified number of containers enables a given volume of concrete to be mixed in the required quality.
A stock of measured quantities of cement and aggregate can be kept in a number of containers, such stock being greater than the immediate requirements on the site where the concrete is mixed and poured. This results in very flexible operation and the concrete requirements can immediately be met without affecting operations at the preparation station. The cement and aggregate should be always accurately measured in practice so that the addition of a predetermined volume of water will given concrete mixes of maximum uniformity. It is more efficient to locate an accurate automatic, semi-automatic, or non-automatic weighing installation and maintain it at the central supply station than to temporarily install and maintain such equipment on a building site.